Boat One
Boat One was the presidential aeroplane of UNIT, created as part of an international agreement on incursion protocols. Under this agreement, in the event of a full-scale invasion a President of Earth with complete authority over every nation state was immediately inducted. It was decided the only practical candidate for this role was the Doctor.
This induction was performed during an invasion of Earth by an army of Cybermen converted from the dead by Missy. Having stumbled upon the invasion, the Twelfth Doctor was captured and taken aboard by UNIT, where he was inducted as Earth's president. Missy was also briefly contained aboard the aircraft.
During flight, the Cybermen attacked the plane. They broke the windows and dragged Colonel Ahmed from the aircraft, while also allowing Missy to escape her confinement. Missy tormented and killed Osgood, before breaching the hull and allowing Kate Stewart, the Doctor and the TARDIS to be blown out of the fuselage.
At Missy's instruction, the Cybermen blew up Boat One. (TV: Death in Heaven)
During the Zygon rebellion, the Doctor requested that they fly on the "presidential plane", which is implied to be Boat One- despite its earlier destruction. The Doctor flies on this plane to Turmezistan and back to the United Kingdom, returning with Osgood and a hostage Zygon. A Zygon disguised as Clara Oswald fired at the plane with a rocket launcher during its return trip. (TV: The Zygon Invasion)
At a later point in Earth's history, the presidential aircraft was instead named the EP One. (AUDIO: War Against the Laan)
